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Questions tagged [dc]

DC stands for Direct Current, which means the flow of electric charge in a single direction. Examples of a DC source are batteries, solar panels, dynamos.

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Using a “noise eating” active low-pass filter

I'm trying to use a MAX281 low-pass IC to filter a DC signal I'm producing on-board. I'm yet to find other chips with the same features so, if you haven't come across them, they're designed to work by ...
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High voltage DC offset servo

I'm working on a project and I need some assistance. I have an audio tube amplifier output stage that I need to have adjustable operating points while maintaining a DC null at the output. [![enter ...
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Protecting Copper Anode in 12V DC System

Getting to grips with cathodic protection here. If someone had a 12, 24 or 48VDC system, say solar PV and batteries, and the battery negative is earthed, this means the earth is the cathode, and the ...
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How to calculate or show in matlab/pspice the DC component from a circuit simulation?

Based on Pspice I'm simulating this RL full wave rectifier That gives the next voltage and current output at the showed probe point The idea is to extract the DC component of the current or voltage, ...
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Isolated vs non-isolated boost converter for LED (12v to 24v)

I have a 12v system in my motorhome and planning on installing 24v LED strips, however, I'm unsure whether I would need an isolated or a non-isolated boost converter. I'll be using roughly 5 meters ...
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31 views

how to choose/design a capacitor value for surge current(for protection) for DC brush motor?

I am driving a DC BRUSH Motor at 30.V.D.C and the current is 300 Millie ampere, it is powered by L.M.317 I.C .My sir is suggesting to provide a capacitor as a protection form surge/peak current ...
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132 views

Use of DC source in Zener clamping circuit

A question in my engineering degree asked me to design a clamp circuit that gives a 10V 50Hz AC signal a +5V DC bias. I designed the following circuit as my answer: I assumed 0.6V forward drop for ...
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1k views

Need a choke coil inductor for DC welder

Working on making an AC 225 volt welder into an AC/DC welder (225 volt AC and 125 volt DC). I purchased bridge rectifier for 225 amp and 220 volts. I am going to use two 3500 uF capacitors and a ...
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304 views

Inrush current in DC DC converter

I am in the process of learning about DC DC converters. What I am trying to figure out is whether inrush current is needed to maintain the input voltage at the DC-DC converter input while getting its ...
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50 views

Does an HEV Genset need a controller?

I am part of a team at school that designs and builds a hybrid electric vehicle. We have chosen to use a series hybrid configuration, so we will be using a motor as a generator to charge lithium ...
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856 views

Using a Ryobi 36v battery to power an electric kart

I'm attempting to use a [BPL3650][1] 36v Ryobi battery as the power source for replica electric willy's jeeps I've constructed for my kids. The batteries charge fine in the standard chargers ...
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78 views

Current across high speed mechanical switch contact even if it can’t be measured?

If I am cycling a mechanical switch at a frequency higher than the bandwidth of a current amplifier and biased using a DC source, is current actually flowing across the contact? The following ...
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186 views

Circuit for voltage division and DC shift doesn't work

I've connected the circuit below on a breadboard and tested it in the lab: Components: \$R_{1}=1\,M\Omega,\;R_{2}=40\,k\Omega,\;R_{3}=R_{4}=R_{5}=R_{7}=R_{8}=20\,k\Omega,\;R_{6}=49.9\,k\Omega\...
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199 views

Raspberry pi B+ internal power supply ckt?

I have just started to study about raspberry pi B+ (data sheet) Can somebody explain the working of power supply circuit (individual component wise) starting from pg 14. How and why it is ...
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60 views

Is this motor suitable for my project?

i have a project which have 4 18volt DC motors, each motor rotate a screw which is 8mm and pitch 1.25mm and 200mm length vertically, load connected via nut in screw, every motor has 3.5 KG load and ...
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511 views

Reverse current frying a boost converter?

AFAIK, most boost converters incorporate a diode or some mechanism for ensuring that current flows from the battery to the output. For instance, TPS61030's datasheet says that This device however ...
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645 views

Application of Fourier Series in Circuit

I am trying to find \$v_o(t)\$ in the circuit below, where $$v_s(t) = 3 - \frac{6}{\pi}\sum_{n=1}^{\infty}\frac{1}{n}\sin2\pi n t$$ The correct answer is $$v_o(t) = \frac{3}{2} - \frac{3}{\pi}\sum_{n=...
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672 views

Stepper motor to replace brushed DC motor to be used to start a gas engine?

I'm trying to decide if it would be possible to use a stepper motor to replace a current 12V DC brushed motor that is used to turn over a small (~149cc) gas engine for starting. The reason why is, I ...
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2k views

DC current amplification

i'm trying to design a battery charger for 5Ah li-ion battery. Due to cost management problems, i am not able to use advanced 5A charger controller ICs; instead, i am going to use a 1A controller with ...
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4k views

Reversing the direction of rotation of a DC cooling fan

We usually connect a small DC cooling fan as show in the diagram. But is there any method to reverse the rotation of this fan in real time, by adding any external circuits?
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371 views

Maverick probe causes ardiuno to reset when touches grounded electrical item

I have a Maverick 732 probe connected to an Arduino for measuring temperature. The outer shield of the probe is connected to the ground pin on the Arduino, and the other wire is connected to an analog ...
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292 views

Control DC circuit with an AC lock switch

I am currently adding circuit with a horn and some lights powered by a motorcycle battery. The circuit should be using about 12v 18A. What I want to do is control the circuit with a lock switch. I've ...
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32 views

DC permanent magnetic motor control issues

We have a 180 V dc permanent magnet motor. When engaging the control board while the motor is hooked up. The output to motor drops out and reads no voltage. If I take the motor leads off the ...
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What is the DC component of the sum of phasors?

I am preparing for the written test conducted by IISc Bangalore for admission into their graduate program. I happened to come across a sample paper from 2016, I think. I am struggling to understand ...
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35 views

Should I add a DC link capacitor between HV battery and buck DCDC converter?

My application does not require an Inverter. If i don't need the capacitor,is it still better to add a resistor to drain any other system capacitance voltage?
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Small 12V DC-Motor Non-Linear Torque vs. Current Curve

I am currently investigating a malfuction on 12V small electric motor. it is performed torque vs. current measurements on a group of samples and some of them are showing non-linear current i.e ...
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76 views

Van conversion electrics

I've been working on the electrics for my van and wondered if anyone could help me. I just accidentally touched some foil bubble wrap insulation to a piece of the van's metal work and it started the ...
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46 views

Controlling a PWM'ed DC fan from 24v instead of 12V source

I have a tiny 12V which consumes ~0.07A and i was wondering if i can PWM the 12V fan with a 24V source at a 50% duty cycle through a ardunio and a mosfet. Would that work or fry the fan as the voltage ...
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31 views

Pickup up DC polarity

We currently have an issue with a project. A client fitted larger motors for windows than specified. We are sending out 12vdc from a BMS interface to open / close with reversing polarity. The new ...
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building real simulation in multisim(NI company) of dc-dc SEPIC convertor

hi I am trying to build real simulationin multisim of dc-dc SEPIC convertor how ever in my output voltage i get a lot of RIPPLE . the problem is that I get a lot of spikes in my capacitor current . ...
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52 views

Advice for PCB layout 230V AC to 18V DC with another function (beginner continued)

I am continuing a thread Beginner's second PCB circuit design: AC to DC Does this PCB design look better than the previous and do you understand it? I also want to know if the terminal blocks ...
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31 views

Can a MTS 101 2 pin ON-OFF switch rated for VAC be used in a DC circuit?

I'm currently looking at buying a bunch of MTS 101 rocker switches which are rated for: AC 125V 6A, AC 250V 3A For DC the rating is not available http://www.massuse-relay.com/details/MTSSeries.pdf ...
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DC signal detection

I have a current source that can output different types of waveform depending on the input, including DC (Howland current pump). I need to find a solution as to make sure that when DC is not required ...
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48 views

Thevenin Equivalent circuit, concept question

I am looking at the circuit in: Apply Thevenin Theorem to a circuit with 2 sources? The circuit and its equivalent have been given as follows in the thread: Circuit: Thevenin Equivalent: Instead ...
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66 views

What calculation can be used to predict the voltage across an air gap as a plasma spark discharges over 1ms?

I am trying to determine what voltage and instantaneous current is available if using a spark gap in air or other gas. Comparable to an auto ignition. This will be DC current. There will be a main ...
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36 views

DC Voltage Multiplier for Positive and Negative Input

I have a small DC motor being driven by a controller which supplies +6V/-6V to the motor to control its speed and direction (elliptical machine resistance control motor). The issue is that 6Vs is not ...
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How to apply Thevenin's theorem in multivoltage(3) sources?

Here is a question I am not able to tackle as the requirement is to solve it by Thevenin's theorem. The question is to find the value of current passing through 20 ohm. I can perform Mesh analysis ...
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51 views

Why aren't homopolar generators more commonly used?

In particular with the advent of HVDC(high voltage direct current). Using mercury(metal), the resistive losses can be greatly reduced. There has even been some experimental research into neon plasma ...
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38 views

DC Variable power supply

I would like some advice on a particular circuit design for a variable DC power supply. Here is some information about what I want to do: I want to do open and short circuit tests on an alternator ...
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65 views

Does applying dc bias to a signal make it stronger?

I worked on a device that mimics a triode vacuum tube. But it doesn't use any vacuum, instead, it uses an electrolyte. I got several of them working, and I can make them switch, by making the "grid" ...
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308 views

How can I design a 12V DC UPS circuit using NMOS?

I have an NMOS with me so I tried to design this 12 V DC UPS circuit after looking at another similar PMOS circuit, but when I open the dc switch, the output is 18kV!! What is the problem with this ...
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71 views

Need help to design a voltage regulator circuit for two 3v dc motors

I intend to use two DC 3V motors to make a mini water pump as described in this video. Here are the specs of my solar panel which i intend to use as power supply for the circuit: Voltage at max ...
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71 views

12V Converter for li ion battery pack supporting 16-20 Amps

I built a 4S Li ion battery pack and I need 12V output at 16-20Amps but I have limited space (70mmx55mm). 12 V would be the best but I could also just reduce the max output from 16.8V (4x4.2V) to ...
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31 views

Isolation of circuitry from heat source

I'm building an electrolysis unit which will comprise a refractory crucible, containing the electrolyte and the electrodes. The heat will be generated from a furnace to aid the desired reaction. A ...
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37 views

Limiting current flow from vehicle DC out to house batteries

Looking to hook up 4 Battle Born 10012 100Ah LiFePO4 batteries in parallel in a Ford Transit van. The Transit has the Ford Programmable Battery Guard option. This option provides a DC terminal that ...
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39 views

DC to DC boost current problem

I am attempting to boost a DC power source (from either 12V20A PSU, 12V 120W car cig port or 14.8V 10aH Lipo) to 26.1V and 6.9A (or 4.5A) using the car cig port taking power limit into account. I am ...
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43 views

AC sources in DC analysis

Can I ground AC voltage sources when I do DC analysis of differential amplifier with BJT and current mirrors circuits?
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87 views

DC disconnector/breaker and battery fuses for 24V 100Ah solar system

I have an off-grid solar system up and running well so far. However, as far as understand there is one essential part is missing in the setup which is the DC disconnector between the inverter and the ...
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38 views

Understanding and finding this DC-DC converter

Reading a circuit, I found the following component: Which is a simple DC-DC converter. There is no possibility to find a datasheet for it. My two questions are: I understand that VO1 is supposed to ...
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46 views

connecting multiple rails of a single dc power supply in parallel

I have a meanwell 24v 10A(Max 14.2A) DC power supply unit having 3 V+ and V- outputs each, i.e a total of 9 outputs including L, N and Gnd. I will be using the unit to power an EC BLDC motor(https://...